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Posted: 4/5/2013 4:57:02 AM EDT
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What is the physical difference on a lower reciever that is marked 5.56/.233 and one marked Multi-Cal?
Could I use a lower marked 5.56/.233 and drop on a upper reciever assembly for say .300 Blackout? I have Local Gun Shop that has a bunch of nice lower recievers made by Double Star for Sog Armory that SOG did not take. I have already built up a couple of them but was thinking maybe grab a few more for a different caliber if it was possible. Thanks |
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The engraving is the only difference. ATF regulations require firearm manufacturers to mark the firearm with, among other things, a caliber. Since the lower is the "firearm" for ATF purposes, it has to be marked with something for caliber, and there is a pretty big number of lowers out there labeled "multi," because that is more accurate than labeling them all ".223 Remington" and having someone quibble about putting a 5.56mm NATO chambered upper on it, let alone a 6.8, or a .300, or... While it might be entertaining and just as useful to mark a lower "Cal: Unicorns," the only real variation from a specific caliber I've seen or heard of has been "Multi."
There are essentially two broad classes of AR-type lowers: AR-15 type lowers that will accept a standard M-16 magazine, and AR-10 type lowers that will accept magazines that hold .308-sized rounds. The magazine well dimensions determine what calibers are usable with a particular lower, either smaller rounds no longer than a .223, or larger rounds no longer than a .308 (though there are a number of different, non-interchangable .308 type lower designs on the market). |
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